(1) Field of the Invention
The present invention relates to miniaturized valves and particularly to such valves which have a fast response time and very low power consumption. More specifically, this invention is directed to exercise of control over the flow of fluids and especially to controlling fluid flow directly from the output of solid state electronic circuitry. Accordingly, the general objects of the present invention are to provide novel and improved apparatus and methods of such character.
(2) Description of the Prior Art
Advances in fluid handling devices have not kept pace with advances in micro-electronics. Accordingly, there is a long-standing desire for a reliable, comparatively inexpensive miniature control valve which has a fast response time. Since control applications generally require that such a valve be used in conjunction with a piston-type actuator, such valves should preferably be of the three-way type. In addition, in order to permit such valves to be mounted directly on circuit boards, and thus operated directly by the micro-electronics, the desired compatible valve must be characterized by very low electrical power requirements.
The typical prior art approach to control valve miniaturization has been simply to attempt to scale down existing valves. These attempts to reduce valve size, however, have been largely unsuccessful and the devices resulting therefrom have been characterized by slow response time and/or unduly high electrical power requirements and/or a high rate of fluid consumption.
A major disadvantage of prior art miniaturized valves resides in the need to constantly bleed fluid when one of the fluid passage-ways controlled by the main valve member is in the closed condition. If the fluid which is employed is contaminated with dirt, this constant bleeding may lead to a clogging of passage-ways which, as the valve becomes physically smaller, become more susceptible to such clogging. Further, miniaturized valves are often used to regulate the flow of expensive fluids such as oxygen and the constant bleeding of the fluid is thus expensive and can, with a flamable fluid, be dangerous.